Causal Intuition and Delayed-Choice Experiments

TL;DR

This paper reexamines delayed-choice experiments through time-symmetric quantum mechanics, revealing conflicts with causal intuition and proposing new perspectives on causality and cosmology.

Contribution

It analyzes delayed-choice experiments using time-symmetric quantum formulations, highlighting their implications for causality and proposing a quantum analog of the classical block universe.

Findings

Time-symmetric formulation predicts experimental outcomes consistent with standard quantum mechanics.

Time-reversed formulation does not match experimental results.

Causal intuition may be fundamentally challenged at the quantum level.

Abstract

The conventional explanation of delayed-choice experiments appears to violate our causal intuition at the quantum level. I reanalyze these experiments using time-reversed and time-symmetric formulations of quantum mechanics. The time-reversed formulation does not give the same experimental predictions. The time-symmetric formulation gives the same experimental predictions but actually violates our causal intuition at the quantum level. I explore the reasons why our causal intuition may be wrong at the quantum level, suggest how conventional causation might be recovered in the classical limit, propose a quantum analog to the classical block universe viewpoint, and speculate on implications of the time-symmetric formulation for cosmological boundary conditions.